1091428889 has 4 divisors (see below), whose sum is σ = 1091514660. Its totient is φ = 1091343120.

The previous prime is 1091428859. The next prime is 1091428909. The reversal of 1091428889 is 9888241901.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 9888241901 = 79 ⋅125167619.

It can be written as a sum of positive squares in 2 ways, for example, as 1024320025 + 67108864 = 32005^2 + 8192^2 .

It is a cyclic number.

It is not a de Polignac number, because 1091428889 - 2¹⁶ = 1091363353 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (1091428859) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 19574 + ... + 50655.

It is an arithmetic number, because the mean of its divisors is an integer number (272878665).

Almost surely, 2^1091428889 is an apocalyptic number.

It is an amenable number.

1091428889 is a deficient number, since it is larger than the sum of its proper divisors (85771).

1091428889 is an equidigital number, since it uses as much as digits as its factorization.

1091428889 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 85770.

The product of its (nonzero) digits is 331776, while the sum is 50.

The square root of 1091428889 is about 33036.7808510454. The cubic root of 1091428889 is about 1029.5919736789.

The spelling of 1091428889 in words is "one billion, ninety-one million, four hundred twenty-eight thousand, eight hundred eighty-nine".